In the testing process of semiconductor devices or semiconductor chips formed on the wafer, the testing is performed by contacting the probe card with electrode pads of the semiconductor devices on the wafer, and collecting signals applied to them. In the past, for this purpose, testing is performed by contacting a probe card such as a cantilever-type probe card having probe pins made of tungsten and the like or a matrix-type probe card having bent pins made of tungsten and the like with a wafer placed on a stage of a prober device, from above on one segment after another. In the test method by using the conventional probe card, since the probe card can contact only a part of semiconductor chips on the entire wafer, the wafer is displaced by the prober device sequentially so as to contact one segment after another of the entire wafer, thereby testing is performed on the entire wafer.
On the other hand, there is a strong demand to raise the test efficiency by decreasing the number of the segments in a contact operation by employing the probe card having a large number of pins. For example, a probe card of the type having a membrane sheet with bumps disclosed in Patent Document 1 or Patent Document 2 has a structure which can provide such a large number of pins, tens of thousands of pins as to meet such demand.
The first conventional mode, a structure of a probe card of the type having a membrane sheet with bumps as disclosed in Patent Document 1 will be explained with reference to FIG. 16. In FIG. 16, reference numeral 201 represents a bumped membrane (membrane sheet with bumps), which is formed by providing bumps 207, short-circuit portions 209 and reverse-face side electrode portions 211 on a polyimide sheet (insulating membrane) 205 which is mounted and spread out on a rigid ring 203. The bumps 207 serve to contact with electrode pads which are lead terminals on the wafer. Reference numeral 213 represents an anisotropic conductive membrane which is constructed by providing an elastic membrane 215 made of rubber material with conductive paths 217 which provide electrical interconnection through the thickness of the conductive paths 217 by compressing the conductive paths 217 in a direction of the thickness thereof. The anisotropic conductive membrane 213 serves to absorb difference in height among the electrode pads of the wafer and among the bumps 207, and to apply contact pressures to the bumps 207, evenly. Reference numeral 219 represents a wiring substrate which comprises an insulating substrate 221 of 3 to 5 mm thickness as a base member, terminals 223, external terminals 225, and lead wires 227 connecting between the terminals 223 and the external terminals 225, respectively. The wiring substrate 219 serves to lead signals which are transmitted from the bumps 207 to the terminals 223 via the conducting paths 217 to the outside. Here, the bumps 207, the short-circuit portions 209, the reverse-face side electrode portions 211, the conductive paths 217 and the terminals 223 are provided in positions corresponding to the electrode pads which serve as lead terminals on the wafer under test (more specifically in the positions coincident with the electrode pads in a horizontal position), and several thousands to tens of thousands of sets are prepared as needed.
Then, the method for producing the bumped membrane 201 is explained with reference to FIGS. 17 to 19. First, a member comprising a copper foil 229 of about 18 μm thickness and a polyimide sheet 205 of about 25 μm thickness affixed to the copper foil 229 is prepared. As shown in FIG. 17, small-diameter holes 231 of about 30 μm diameter are formed in the polyimide sheet 205 by irradiating the polyimide sheet 205 with laser (the first step). Next, a protective resist 233 is applied to the reverse side of the copper foil 229, and nickel electroplating is performed by connecting a plating electrode to the copper foil 229. The nickel is plated in such a manner as to fill in the small-diameter holes 231 to form the short-circuit portions 209. After reaching the surface of the polyimide sheet 205, nickel plating spreads uniformly to all directions into a hemisphere, thereby forms the bump 207 (the second steps, refer to FIG. 18). The nickel plating is performed until each bump 207 reaches 10 to 20 μm in height. Then the protective resist 233 applied to the reverse side of the copper foil 229 is stripped, another resist is applied again to the reverse side of the copper foil 229, and a pattern for the reverse-face side electrode portions is exposed on the resist. The reverse-face side electrode portions 211 are formed by etching the copper foil 229. Then the resist is removed, and the polyimide sheet 205 is affixed to the rigid ring 203, thereby the bumped membrane 201 is completed (the third step, refer to FIG. 19).
Next, the second conventional mode, the structure of the probe card of the type including a membrane sheet with bumps as disclosed in Patent Document 2 is described with reference to FIGS. 20 to 29.
This probe card has a frame plate 301 shown in FIG. 20. The frame plate 301 has a diameter of 200 mm to 300 mm which is almost equal to a diameter of a wafer under test, and a thickness, for example, of about 40 μm to 80 μm. And, the frame plate 301 has a thermal expansion coefficient or linear thermal expansion coefficient close to that of the wafer in order to avoid influence of positional misalignment accompanied by temperature change. The frame plate 301 has the thermal expansion coefficient or linear thermal expansion coefficient, for example, of 0 to 1×10−5/° C. Further, the frame plate 301 has a plurality of through-holes or through-bores 303 penetrating through in a thickness direction of the frame plate 301. The through-holes or through-bores 303 are formed in the frame plate 301 by etching so as to correspond to the semiconductor chips formed on the wafer.
FIG. 21 shows a structure of an area of the through-hole 303 formed in the frame plate 301, and an anisotropic conductive membrane 305 and a contact membrane (membrane sheet with bumps) 307 are supported by and mounted on a periphery of through-hole 303. The anisotropic conductive membrane 305 comprises an elastic membrane 309 and conductive paths 311 provided in the elastic membrane 309, this elastic membrane 309 is made of rubber material and has 80 μm thickness. An outer periphery (313) of the elastic membrane 309 is fixed to a periphery of the through-hole 303 on the frame plate 301, and the elastic membrane 309 serves to retain the conductive paths 311.
The conductive path 311 comprises a part of 130 μm thickness in an elastic membrane and a large number of metal particles contained in the part, therefore comes to have an electric conductivity in upward and downward directions due to contacts among the metal particles contained in the conductive path 311 as a result of deformation of the conductive path 311 when a load is applied to the conductive path 311 in a thickness direction of the conductive path 311.
On the other hand, the contact membrane 307 comprises an insulating membrane 315, bumps 317 formed on a face side of the insulating membrane 315 and conductive electrodes 319. The insulating membrane 315 is made of polyimide and has 25 μm thickness. A peripheral portion or a reverse face of the peripheral portion of the insulating membrane 315 is fixed to the frame plate 301 with an adhesive 321. The insulating membrane 315 is provided with the bumps 317 on the face side of the insulating membrane 315, and each bump 317 is made of nickel and is about 20 μm in diameter as well as in thickness. The bump 317 serves to contact with an electrode pad of the semiconductor chip on the wafer. Further, the insulating membrane 315 is provided with conductive electrodes 319 in a surface of the insulating membrane 315 and in the insulating membrane 35, each leads to the bump 317. The conductive electrodes 319 serve to connect between the bump 317 and the conductive path 311 in the anisotropic conductive membrane 305. Reference numeral 323 represents a wiring substrate having a large diameter corresponding to the wafer, and the wiring substrate 323 comprises a 3 to 5 mm thick insulating substrate 325 which is a base member, terminals 327, external terminals 329 and lead wires 331, and serves to lead signals which are transmitted from the bump 317 to the terminal 327 via the conductive electrode 319 and the conductive path 311, to the outside through the external terminal 329.
Now, the method for producing the contact membrane 307 is described below, with reference to FIGS. 22 to 29.
In FIG. 22, reference numeral 333 represents a ply sheet, in which a large number of the contact membranes 307 are to be formed. FIG. 23 is a view showing a cross-section of the ply sheet 333, and the ply sheet 333 comprises a 25 μm thick polyimide sheet 335 to provide the insulating membranes 315 and a 4 μm thick copper foil 337 affixed thereto. Then, a resist 339 is applied to the ply sheet 333, and a pattern for the conductive electrodes are formed on the resist 339 by using photo-masking process to form the conductive electrodes on positions corresponding to the electrode pads of semiconductor chips on the wafer. And the ply sheet 333 is dipped in a polyimide etching solution, and conductive electrode holes 341 are formed in the polyimide sheet 335 (333) by using the pattern formed in the resist 339 as masking (the first step, refer to FIG. 24). In this case, as shown in FIG. 24, due to anisotropic properties of the polyimide, a cone-shaped hole (a hole with trapezoidal cross-section) with a sidewall angle of 50° relative to a face of the ply sheet 333 is etched gradually in the ply sheet 333. Then, the resist 339 is stripped, nickel plating is carried out by using the copper foil 337 as a plating electrode, nickel is deposited in the conductive electrode holes 341 about to the thickness of the polyimide sheet 335, and thereby the conductive electrodes 319 are formed, as shown in FIG. 25 (the second step). After the conductive electrodes 319 are formed, another resist 342 is applied to the copper foil 337, bump holes 343 are formed in the resist 342 by photo-masking process in order to form bumps 317 in positions corresponding to the electrode pads of the semiconductor chips (the third step, refer to FIG. 26). Furthermore, as shown in FIG. 27, nickel plating is carried out by using the copper foil 337 as a plating electrode, and nickel is deposited in the bump holes 343 to a height which does not exceed to the thickness of the resist 342, thereby the bumps 317 are formed (the fourth step). Then, the resist 342 is stripped, another resist 345 is applied, and a pattern is formed in the resist 345 by using photo-masking process. The polyimide sheet 335 in this condition is dipped in an etching solution for etching copper, the copper foil 337 is etched away, thereby formed is each conductive electrode base 347 in a periphery of each bump 317. The conductive electrode base 347 serves as a part of the conductive electrode 319 (the fifth step, FIG. 28). Afterwards, the resist 345 is stripped, and rectangular parts as in FIG. 22 are cut out and separated from the polyimide sheet 335 to obtain individual contact membranes 307. Then, non-defective contact membranes 307 are sorted out of the obtained contact membranes 307, and each of the non-defective membranes 307 is applied with the adhesive 321 as shown in FIG. 29, and is mounted on the frame plate 301 with respect to each through-hole 303 by using a mounting device as shown in FIG. 21. Finally, the frame plate 301 is entirely placed on the wiring substrate 323 or on a face side of the wiring substrate 323, thereby the probe card is completed.